Magnetic tunnel junction with iron dusting layer between free layer and tunnel barrier

Abstract

A magnetic tunnel junction (MTJ) for a magnetic random access memory (MRAM) includes a magnetic free layer having a variable magnetization direction; an iron (Fe) dusting layer formed on the free layer; an insulating tunnel barrier formed on the dusting layer; and a magnetic fixed layer having an invariable magnetization direction, disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer; wherein the free layer and the fixed layer have perpendicular magnetic anisotropy and are magnetically coupled through the tunnel barrier.

1 . A method of forming a magnetic tunnel junction (MTJ) for a magnetic random access memory (MRAM), the method comprising:
 forming a magnetic free layer having a variable magnetization direction;   forming an iron (Fe) dusting layer over the free layer;   forming a tunnel barrier comprising an insulating material over the Fe dusting layer; and   forming a magnetic fixed layer having an invariable magnetization direction over the tunnel barrier, wherein the free layer and the fixed layer have perpendicular magnetic anisotropy and are magnetically coupled through the tunnel barrier.   
     
     
         2 . The method of  claim 1 , wherein forming the tunnel barrier comprises one of radical oxidation, natural oxidation, and radiofrequency (RF) sputtering. 
     
     
         3 . The method of  claim 2 , wherein the tunnel barrier comprises magnesium oxide (MgO) that is formed by radical oxidation of a first layer of magnesium (Mg), and is capped by a second layer of Mg formed on the radically oxidized MgO. 
     
     
         4 . The method of  claim 1 , wherein the Fe dusting layer is formed by sputtering. 
     
     
         5 . The method of  claim 1 , wherein the free layer comprises cobalt-iron-boron (CoFeB), and wherein forming the free layer comprises growing the free layer on a seed layer comprising one of tantalum (Ta) and tantalum magnesium (TaMg). 
     
     
         6 . The method of  claim 1 , further comprising forming an interfacial layer between the tunnel barrier and the fixed layer, the interfacial layer comprising a layer of Fe and a layer of CoFeB. 
     
     
         7 . The method of  claim 1 , further comprising forming a tantalum spacer between the interfacial layer and the fixed layer. 
     
     
         8 . The method of  claim 1 , further comprising forming a dipole layer adjacent the free layer, wherein the free layer is located between the dipole layer and the tunnel barrier.